As you have not specified if you already copied the agent to your system i will take it from the start:
(all below is done via commandline and as root or prepend commands with sudo if you have this mechanism in place)
make sure you have the wget package available on the system you want to install the agent on, if not install it with apt install wget
Find the download link of the Debian package in your CheckMK server via sidebar menu → Setup → Subsection Agents → Linux
copy link location of the ‘Packaged Agent ending with .deb’